Extraction of ductile pipe

ABSTRACT

A pipe extraction machine can be used to remove a buried pipe from the ground. The machine has a carriage with jaws that grip the buried pipe. While gripped, the carriage moves relative to a support structure to pull the pipe out of the ground. Jaws are actuated by rotating clamp plates and maintained in opposition by static horizontal grooves. The jaws remain opposed and aligned during rotation of the clamp plates. A pipe shear may remove the pipe one piece at a time. A pipe puller can be used at the back end of the pipe being removed to simultaneously install a new pipe along the same path.

FIELD

The present invention relates generally to the extraction of pipe frombelow the ground.

SUMMARY

The present invention is directed to an apparatus. The apparatuscomprises a support structure and a carriage. The carriage is movablerelative to the support structure. The carriage comprises a carriageframe and a pipe clamp assembly. The carriage frame comprises aplurality of second slots. The pipe clamp assembly is supported by thecarriage frame and comprises a rotatable plate, a first jaw, a secondjaw, a first pin, and a second pin. The rotatable plate is characterizedby a plurality of first slots. The first pin is disposed through thefirst jaw, one of the plurality of first slots, and one of the pluralityof second slots. The second pin is disposed through the second jaw, oneof the plurality of first slots, and one of the plurality of secondslots.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagrammatic representation of an excavation site.

FIG. 2 is a top back left view of an extraction machine.

FIG. 3 is a top front right view of the extraction machine of FIG. 2.

FIG. 4A is a front plan view of the extraction machine of FIG. 2, withthe pipe shear in an open position.

FIG. 4B is the front plan view of FIG. 4A, with the pipe shear in acutting position.

FIG. 5A is a left side view of the extraction machine with a side wallremoved. The carriage is retracted and the jaws are in an open position.

FIG. 5B is a view of the extraction machine along line A-A in FIG. 5A.

FIG. 6A is a left side view of the extraction machine with a side wallremoved. The carriage is extended and the jaws are in the closedposition.

FIG. 6B is a view of the extraction machine along line B-B in FIG. 6A.

FIG. 7A is a top right view of a clamp mechanism for use in theextraction machine, with jaws in a partially closed position.

FIG. 7B is a top right view of the clamp mechanism of FIG. 7A with thejaws closed more fully than in FIG. 7A.

FIG. 8 is a top right side view of a pipe puller.

FIG. 9A is a side view of a pipe having been crushed by the jaws.

FIG. 9B is a sectional view of the pipe of FIG. 9A along section D-D.

FIG. 9C is a sectional view of the pipe of FIG. 9A along section C-C.

DETAILED DESCRIPTION

Methods for crushing ductile pipe and subsequently pulling or extractingsaid pipe from the ground are shown in U.S. Pat. No. 7,128,499, (“the'499 patent”) issued to Wentworth, the contents of which areincorporated herein by reference. In Wentworth and other conventionalsystems, lever arms provide clamp force for crushing and grippingductile pipe between opposed jaws. The jaws are urged away from theground by actuators, extracting the pipe. In compact designs, the clampforce that can be achieved by such lever arms may be in the range of2.5-4.5 times the thrust force required to extract the pipe from theground. This requires a coefficient of friction between the jaws andpipe of 0.40 to 0.22 to avoid slippage. These numbers are achievable butthe pipe may slip and cause the extraction method to be unsuccessful.

Thus, one limiting factor in such extraction operations is thegrip-to-thrust ratio of the apparatus. Strong actuators are no use ifthe pipe, flattened by jaws, slips from them.

The '499 patent overcame some of these issues through use of a wire ropestrand, which would attach through the existing pipe to a product pipepuller at the opposite side of the pipe being extracted. The strandprovided an additional pulling force to overcome the initial friction ofthe surrounding ground. However, the strand would often need to be cutwith the extracted pipe during extraction, causing this element to besacrificial. Cutting the strand, rather than the pipe alone, causedcutting elements to dull prematurely. It is advantageous not to cutthrough a strand with a blade. Finally, installation of the strand istime-consuming.

The present invention provides an improvement to aid in the eliminationof the strand from the system. The machine described herein utilizes acamming clamp mechanism to produce a clamp force much greater than whatcan be achieved with lever arms. The crushing force may exceed fivetimes the thrust force, and may in fact be 7-10 times the thrust forcerequired to extract the pipe from the ground. Therefore, the coefficientof friction required to avoid slippage drops to 0.14-0.10, a veryattainable value. The camming clamp mechanism may apply a force to thepipe of 100-140 tons, with half of the force applied by each jaw.

The load required to break a pipe, often installed for decades, awayfrom surrounding soil, may be as high as 3.5 lbs of force per squareinch of pipe external surface area. Upon breakaway, the stress requiredto continue movement of the pipe drops significantly, perhaps 50%-75%.The high clamp force enables the system to pull a pipe with a length ofgreater than thirty feet from end to end without the use of a strand. Infact, lengths of greater than fifty feet or greater than one hundredfeet may be extracted.

Replacement pipes are optionally installed behind a pipe beingextracted. These replacement pipes are often made of HDPE (high densitypolyethylene). Pipe pullers may be utilized to connect the pipe beingextracted to the new pipe so that the new pipe follows the same path asthe existing pipe.

With reference now to FIG. 1, a typical excavation area 10 for use withthe present invention is shown. A pit 12 has been dug below a surface 11in soil 20. The pit 12 provides access to an underground pipe 14 to beextracted. Often, pipe 14 will be a lateral pipe that was previouslyconnected to a mainline 13. The pit 12 typically has a width 15 that isrelatively compact. This necessitates that section of pipe 14 areremoved in pieces. The pipe 14 to be replaced extends only a smalllength 19 away from a face 21 of the pit, and only a height 17 from afloor of the pit. Therefore, an extraction machine should operate incompact environments.

The pipe 14 is connected at its far end 16 to a pipe puller 70. The pipepuller 70 connects the pipe 14 being extracted to a new pipe 18 beinginstalled during the extraction process.

The present invention, as shown in FIGS. 2 and 3, is directed to a pipeextraction machine 30. The machine 30 comprises a support structure,referred to herein as a hull 80, and a machine carriage 31. The machinecarriage 31 is movable relative to the hull 80 through the extension andretraction of linear actuators 39. The actuators 39 shown are hydrauliccylinders having a rod 33 and a barrel 38, though rack and pinions,screws, or other actuators may be utilized.

The carriage 31 comprises a carriage frame 37, two or more pipe camcylinders 41, and a clamp mechanism 45 (FIG. 5) supported by the frameand actuated by the pipe cam cylinders. The carriage 31 generallydefines a central pipe throat 32 for location of the pipe 14 duringextraction.

The hull 80 comprises a reaction plate 82, side walls 84, and a wheelguide 88. The actuators 39 extend between the carriage 31 and thereaction plate 82. The reaction plate 82 defines a pipe service slot 85that allows a pipe into the extraction machine 30. Side walls 84 aregenerally orthogonal to the reaction plate 82 and have an upper surface83 that is generally oriented horizontally. The wheel guide 88 is on andabove the upper surface 83. The machine carriage 31 comprises wheels 35which extend from the carriage into a slot defined by the wheel guide 88and the upper surface 83.

The wheels 35 support the carriage structure 31. The wheels 35 cause thecarriage 31 to be movable relative to the hull 80 through operation ofthe actuators 39 in a direction parallel to a pipe 14 (FIG. 1) beingextracted. The hull 80 may have one or more lift points 81 forattachment to a chain or strap to move the extraction machine 30.

The carriage 31 comprises a pipe shear 60 and a clamp mechanism 45having jaws 34. The clamp mechanism 45 is preferably located between thepipe shear 60 and the reaction plate. In this way a pipe 14 (FIG. 1) maybe held by the jaws 34 while the pipe is being cut by the pipe shear 60.

The pipe shear 60, as shown best in FIGS. 3, 4A and 4B, comprises ashear actuator 64, a movable shear blade 61, guide plates 62 and a fixedshear blade 68. The actuator 64 moves the movable shear blade 61relative to a pin connection 65 between the actuator and the carriageframe 37. As shown the actuator 64 is a cylinder, though other linearactuators may be used. Guide plates 62 guide the shear blade 61 as itmoves slidably relative to the fixed shear blade 68.

The movable shear blade 61 comprises a flat member having a closedopening formed therein. Preferably, the opening is circular in shape andincludes a sharpened edge 67. The fixed shear blade 68 likewisecomprises a flat member with a closed opening formed therein. Theopening is preferably circular in shape and includes a sharpened edge69. The openings of blades 61, 68 are alignable. When aligned, theopenings are concentric. These openings are aligned with a pipe throat32 as shown in FIG. 4A. A pipe 14 enters the pipe throat 32 and passesbetween jaws 34 and the openings of blades 61, 68.

Through movement of the shear actuator 64, the moving shear blade 61slides relative to the fixed shear blade 68. The sharpened edges 67, 69of blades 61, 68 move out of alignment as in FIG. 4B. A pipe or cablewithin the openings is therefore cut.

The movable shear blade 61 may include a plurality of eyes 66. Theseeyes 66 permit inversion or other repositioning of the movable blade 61relative to the fixed blade 68. As portions of the movable blade 61become dull, such repositioning can bring sharper portions of the blade61 into use. The fixed shear blade 68 may be removable from the carriage31 for repairs, replacement, or sharpening.

With specific reference to FIGS. 5A-7B, the clamp mechanism 45 comprisesthe pipe clamp jaws 34, a first cam plate 46, a second cam plate 47 andpipe cam cylinders 41. The plates 46, 47 are two similar heavy platessurrounding the central pipe throat 32. These plates 46, 47 areconnected by one or more pins 55. The pins 55 may be plugs welded to theplates.

The pipe cam cylinders 41 each have an extendable rod 42. The rods 42attach at pins 54. When the rods 41 extend and retract, the plates 46,47 rotate around the pipe throat 32. The cam plates 46, 47 ride onwheels 40 that facilitate rotation around the pipe throat. The wheels 40are supported by the carriage frame 37.

The pipe cam cylinders 41 operate out of sequence, such that when thecylinder rod 42 of one cylinder is extending, the corresponding cylinderrod of the other is retracting. The pipe cam cylinders 41 are eachsubstantially vertical. In one embodiment, the pipe cam cylinders 41 areno more than 45 degrees from a vertical orientation.

The pipe clamp jaws 34 are disposed between the plates 46, 47. The pipeclamp jaws 34 each comprise a crush face 43. Preferably, the crush face43 is durable and rough to increase the frictional force between thejaws 34 and a pipe. The crush faces 43 of the jaws 34 are situated inparallel relationship.

Each of the pipe clamp jaws 34 has a follower pin 48 in its upper andlower corner furthest from the pipe throat 32. Each of the first camplate 46 and second cam plate 47 define curved cam path grooves 49. Thepins 48 are disposed through cam path grooves 49.

The pins 48 may comprise one or more bushings 53. The bushings 53facilitate ease of movement of the pins 48 within the associated groovesduring operation of the clamp mechanism 45. Pins 48 may include greasefittings for the same purpose.

With reference again to FIG. 2, a face plate 56 is a part of thecarriage frame 37. As shown, the face plate 56 faces the reaction plate82 of the hull 80. Four horizontal or rectilinear tracks or grooves 58are formed in the carriage frame 37. In one embodiment, the grooves 58are in the face plate 56. Follower pins 48 extend through the face plate56 at these grooves 58. Motion of the follower pins 48 are restricted tothe horizontal grooves 58. A similar face plate (not shown) may beprovided on the opposite side of the carriage 31.

Grooves 58 are stationary and parallel. The grooves 58 maintain aposition of the pins 48 relative to the face plate 56. The grooves 58coordinate to keep the crush faces 43 of the jaws 34 parallel andvertical. Grooves 49 cause the pins 48 to move closer or further fromthe pipe throat 32. Any cam surface, such as cam groove 49, may beutilized to engage the pins 48.

As plates 46 and 47 are rotated, the jaws 34 move in opposingdirections. Depending on the rotational direction of the plates 46, 47,the jaws either move toward or away from the center of the throat 32.When actuated toward one another, the jaws 34 coordinate to crush orpinch a pipe (not shown) disposed within the pipe throat 32 from twosides.

As shown in FIGS. 4B and 5B, clockwise rotation of the plates 46, 47results in the jaws 34 moving away from one another. Counter-clockwiserotation of the plates 46, 47 results in the jaws 34 moving toward oneanother. The clock directions of plate rotation that produce these jawmotions may be reversed if desired.

As shown best in FIGS. 7A and 7B, the groove 49 may have two portions. Afirst portion 49A, which contains the follower pin 48 when the jaws 34are open, is short and steep. Thus, when the plates 46, 47 are rotatedwith the pin 48 in this portion, 49A, modest forces are applied at thejaw crushing faces 43 while using little of the available plate 46, 47rotation.

A second portion 49B is less steep, such that the jaws 34 move less witha higher angular travel of the plates 46, 47. Thus, greater force isprovided by the pipe cam cylinders 41 to the jaws 34 and their crushfaces 43 when the pin is within second portion 49B.

The cam plates 46, 47 comprise peripheral hooks 50. The hooks 50 blockperipheral movement of the wheels 40 around the cam plates 46, 47. Forexample, in FIG. 5B, contact between a hook 50A and wheel 40A preventsfurther rotation in the clockwise direction. In this position, the jaws34 are at their maximum distance from one another. Similarly, in FIG.6B, a hook 50B contacts wheel 40B, preventing further rotation in thecounter-clockwise direction.

If a pipe (not shown) is within the pipe throat 32 and fully crushed,the space between opposing crush faces 43 will be approximately two wallthicknesses. In one embodiment, the hooks 50 will block peripheralmovement of the wheels 40 (FIGS. 4B, 5B) only when the crush faces 43are less than two wall thicknesses apart. The clamp mechanism 45 cantherefore continue to apply force to the crushed pipe even when the pipeis fully crushed.

In operation, a pipe 14 to be extracted is disposed through the pipethroat 32 of the carriage 31. The actuators 39 are preferably unextendedas shown in FIG. 5A, and the jaws 34 are open. The reaction plate 82 ofthe hull 80 is secured against the face 21 of the pit 12.

The pipe cam cylinders 41 rotate the cam plates 46, 47 to close the jaws34. Rotation of the cam plates 46, 47 causes the pins 48 to travel ingrooves 58 of the face plate 56. Thus, the jaws 34 close in the pipethroat 32, crushing the pipe 14 with substantially equal and alignedforces on opposite sides of the pipe.

The resulting pipe shape is shown in FIGS. 9A, 9B and 9C. In thesefigures, a zone 90 of ductile pipe 14 has been crushed and flattened byclamp jaws 34. The zone 90 has an undeformed area 91, a transition zone93, and a flattened area 94. The flattened area 94 has contacted thepipe jaws 34 through the entire width of the flattened area. Thetransition zones 93, located on either side of the flattened area 94,transition the pipe 14 from the undeformed area 91 to the fullyflattened profile 94.

During the next stage of operation, the jaws 34 remain closed andcontinue to exert force on the parallel surfaces 95. The carriage 31 ispushed away from the reaction plate 82 by the actuators 39. The pipe 14is accordingly pulled with the carriage 31 out of the ground. The pipe14 is held by the friction between the flattened area 94 and theactuated jaws 34. If the pipe should slip within the jaws 34 at theflattened area 94, such slippage should be limited by engagement of theadjacent transition area 93 with the jaws 34. Thus, if the forcerequired to extract the pipe exceeds the frictional limit of theflattened area 94, the pipe remains engaged with the moving carriage 31at the transition area 93.

When the actuators 39 are at their full stroke, the pipe shear 60 may beactivated to shear off the length of pipe 14 that has been extracted.The jaws 34 are then released by rotating the cam plates 46, 47 in theopposite direction. The actuators 39 may then retract, pulling thecarriage 31 back towards the reaction plate 82 for a subsequent stroke.

The machine 30 therefore breaks the initial friction between the pipe 14and the soil 20 without the use of a cable or strand within the pipe 14.The clamp force of jaws 34 is sufficient to hold the pipe 14 duringinitial and subsequent strokes of the carriage 31.

The foregoing steps are repeated until the pipe is fully extracted frombeneath the ground. Removed segments of pipe may be discarded.

Optionally, a new pipe 16 (FIG. 1) may be pulled behind the pipe 14,with the new pipe 16 following the path of the old pipe 14. Because nostrand is extends through the pipe 14, the new pipe 16 must beinterconnected with the pipe 14.

With reference to FIG. 8, the pipe puller 70 is shown. The pipe puller70 has a front puller 71 and a rear puller 72 connected by a pivot 73.The pivot 73 allows the pipe puller 70 to accommodate bends. As shown,the pivot 73 comprises two pivot points, each allowing the pipe puller70 to pivot about a different axis. In one embodiment, shown in thefigures, those axes are perpendicular to one another.

The front puller 71 may be threaded into a back end of the pipe 14 beingpulled by machine 30. A new product pipe (not shown) may be likewiseattached or threaded to the rear puller 72. An expander 79 may beutilized between the pullers 71, 72 to increase a diameter of aresulting bore. In one embodiment, the expander may increase thediameter of the resulting bore to 20% or more of the diameter of the newpipe 16.

The pipe 14 is extracted along its path 78. The new pipe 16 can beinstalled along a similar path 77 as the pipe 14 is being extracted. Thesimultaneous extraction and installation along similar paths minimizesdisruption to other buried lines.

The various features and alternative details of construction of theapparatuses described herein for the practice of the present technologywill readily occur to the skilled artisan in view of the foregoingdiscussion, and it is to be understood that even though numerouscharacteristics and advantages of various embodiments of the presenttechnology have been set forth in the foregoing description, togetherwith details of the structure and function of various embodiments of thetechnology, this detailed description is illustrative only, and changesmay be made in detail, especially in matters of structure andarrangements of parts within the principles of the present technology tothe full extent indicated by the broad general meaning of the terms inwhich the appended claims are expressed.

The invention claimed is:
 1. A method comprising: placing a pair of jawson opposing sides of a pipe, wherein the pipe is partially buried in theground; moving the jaws directly toward one another along opposing,straight-line paths until the pipe is gripped between the jaws at afirst position by performing the step of: rotating a plate such thateach jaw is continuously engaged by a cam surface disposed on the plate;while the pipe is gripped by the jaws at the first position, pulling alength of the pipe out of the ground with the jaws.
 2. The method ofclaim 1 further comprising: shearing away a portion of the pipe afterpulling the length of the pipe out of the ground.
 3. The method of claim1 further comprising: moving the jaws directly away from one anotheralong the opposing, straight-line paths until the pipe is not grippedbetween the jaws; and moving the jaws along the pipe such that the jawsremain on opposing sides of the pipe.
 4. The method of claim 3 furthercomprising: after moving the jaws along the pipe, moving the jawsdirectly toward one another along the opposing, straight-line pathsuntil the pipe is gripped between the jaws at a second position; andwhile the pipe is gripped by the jaws at the second position, pulling asecond length of the pipe out of the ground with the jaws; wherein thefirst position and second position are longitudinally spaced along thepipe.
 5. The method of claim 4, further comprising: after the step ofpulling the length of the pipe out of the ground with the jaws at thefirst position, and before the step of pulling the second length of thepipe out of the ground with the jaws at the second position, shearingaway a portion of the pipe.
 6. The method of claim 1, wherein: the jawsare situated on a carriage, the carriage comprising: a carriage framewithin which one or more rectilinear tracks is formed; wherein the jawseach comprise a follower riding in one of the one or more of therectilinear tracks.
 7. The method of claim 6 wherein each of the one ormore of the rectilinear tracks is parallel to the opposing,straight-line paths.
 8. The method of claim 1 in which the step ofmoving the jaws directly toward one another along the opposing,straight-line paths until the pipe is gripped between the jaws at thefirst position comprises: deforming the pipe with the jaws.
 9. Anapparatus comprising: a stationary support structure; and a carriagemovable relative to the stationary support structure comprising: acarriage frame; a pipe clamp assembly supported by the carriage frameand characterized by a first jaw and a second jaw, each of the first jawand second jaw having a face opposed to the face of the other jaw; andan actuator to move the first jaw in a first direction and to move thesecond jaw in a second direction while maintaining the faces in anopposing relationship, wherein the first and second directions areopposite and straight; wherein the actuator comprises a first cylinderoriented no more than 45 degrees from vertical.
 10. The apparatus ofclaim 9 in which the face of each of the first jaw and the second jaware planar and parallel.
 11. A system comprising: the apparatus of claim9; and a pipe disposed between the opposed faces of the first jaw andthe second jaw.
 12. The system of claim 11, wherein the pipe is deformedbetween the opposed faces of the first jaw and the second jaw.
 13. Amethod of using the apparatus of claim 9, comprising: disposing a pipebetween the first jaw and the second jaw; thereafter, with the actuator,moving the first jaw in the first direction and moving the second jaw inthe second direction until the first jaw and second jaw grip the pipe;while gripping the pipe with the first and second jaw, moving thecarriage relative to the stationary support structure.
 14. The method ofclaim 13, further comprising crushing the pipe with the first jaw andthe second jaw prior to the step of moving the carriage.
 15. The methodof claim 13: in which the carriage frame defines one or more rectilinearslots; in which the pipe clamp assembly comprises: a plate rotatablerelative to the carriage frame, the plate comprising one or more curvedslots; a first pin disposed through the first jaw, one of the one ormore curved slots, and one of the one or more rectilinear slots; and asecond pin disposed through the second jaw, one of the one or morecurved slots, and one of the one or more rectilinear slots; and in whichthe step of moving the first jaw and moving the second jaw with theactuator comprises: causing the plate to rotate relative to the carriageframe such that the first pin and second pin are moved toward oneanother in the one or more rectilinear slots.
 16. The method of claim15, further comprising crushing the pipe with the first jaw and thesecond jaw prior to the step of moving the carriage.
 17. An apparatuscomprising: a stationary support structure; and a carriage movablerelative to the stationary support structure comprising: a carriageframe; a pipe clamp assembly supported by the carriage frame andcharacterized by a first jaw and a second jaw, each of the first jaw andsecond jaw having a face opposed to the face of the other jaw; and anactuator to move the first jaw in a first direction and to move thesecond jaw in a second direction while maintaining the faces in anopposing relationship, wherein the first and second directions areopposite and straight; in which the carriage frame defines one or morerectilinear slots and in which the pipe clamp assembly comprises: afirst pin disposed through the first jaw, and one of the one or morerectilinear slots; and a second pin disposed through the second jaw, andone of the one or more rectilinear slots.
 18. The apparatus of claim 17in which the pipe clamp assembly further comprises: a plate rotatablerelative to the carriage frame, the plate defining one or more curvedslots; wherein: the first pin is disposed through one of the one or morecurved slots; and the second pin is disposed through one of the one ormore curved slots.